Dust collecting element and process for making the same



H. W. WEBB Dec. 10, 1940.

DUST COLLECTING ELEMENT AND PROCESS FOR MAKING THE SAME Filed Nov. 9, 1934 6 Sheets-Sheet 1 wxmm Q & Q

Dec. 10, 1940. w, WEBB 1 DUST COLLECTING ELEMENT AND PROCESS FOR MAKING THESAME Filed Nov. 9, 1934 6 Sheets-Sheet 2 H. W. WEBB Dec. 10, 1940.

DUST COLLECTING ELEMENT AND PROCESS FOR MAKING THE SAME Filed NOV. 9, 1934 6 Sheets-Sheet Dec. 10, 1940. H. w. WEBB DUST COLLECTING ELEMENT AND PROCESS FOR MAKING THE SAME Filed Nov. 9, 1934 6 Sheets-Sheet 4 m all: x. .1 wok w y 2 \IH4 i l|ll H. W. WEBB Dec. 10, 1940.

DUST COLLECTING ELEMENT AND PROCESS FOR MAKING THE SAME Filed Nov. 9, 1934 6 Sheets-Sheet 5 Dec. 10, 1940. w B 2,224,172

DUST COLLECTING ELEMENT AND PROCESS FOR MAKING THE SAME Filed Nov. 9, 1934 6 Sheets-Sheet s Patented Dec. 10, 1940 -PATENT- OFFICE DUST COLLECTING ELEMENT AND PROCESS FOB IHAKINGIv THE SAME Hartwell w. Webb. Flint, Mich, assignor to General Motors Corporation, Detroit, Mich a corporation of Delaware Application November 9, 1934, Serial No. 752,232

16 Claims.

This invention relates to apparatus for removing dust from air and, in particular, to a dustcollecting element which consists of a liquidcoated interstitial body through which air is I adapted to pass and on whose liquid-coated surfaces the dust in the air is adapted to be caught and retained. The principal object of this invention is to provide a dust-collecting element of the type de- 10 scribed which will offer low, uniform and stable resistance to the passage of air and yet will afford a suflicient area of liquid-coated surface to insure that the air which passes therethrough will be thoroughly freed from dust. It is a further obiect of this invention to provide a dust-collecting element with the described characteristics which may be produced cheaply and economically and to provide a process and apparatus for producing it cheaply and economically.

For a better understanding of the nature and objects of this invention, reference is made to the following specification and the accompanying drawings wherein the invention is described and illustrated.

In the accompanying drawings:

Figure 1 is a side elevation of the machine which I have designed for producing the dust-collecting element to which this invention relates;

Figure 2 is a plan view of the machine;

Figure 3 is an enlarged fragmentary elevation of one of the spindle-carrying fixtures of the machine, viewed as indicated by the line 3-3 of Figure 1, with a spool of wire mounted on the illustrated spindle;

Figure 4 is an enlarged section, taken on the line 4-4 of Figure 2, of the first wire-deforming element and associated parts of the machine.

Figure 5 is an enlarged fragmentary end ele- 40 vation of the first wire-deforming element,

viewed as indicated by the line 5-5 of Figure 2;

Figure 6 is an enlarged view, partly in side elevation from the standpoint indicated by the arrows 6-45 of Figure '7 and partly in section of the 45 wire-flattening element of the machine;

Figure '7 is an enlarged view, partly in end elevation and partly in section, of the wire-flattening element;

Figure 8 is an enlarged end elevation of the 50 second wire-deforming element of the machine with a part broken away so that the view of the rolls will not be obscured;

Figure 9 is a further enlarged fragmentary section through the rolls of the second-wire deforming element taken in the plane of the axes of the rolls;

Figure 10is an end elevation of the part of the second wire-deforming element which is broken away in Figure 8;

Figure 11 is an enlarged fragmentary view of the winding element of the machine taken as indicated by the line I l-l lof Figure 1;

Figure 12 is an enlarged fragmentary longitudinal section through the winding element:

Figure 13 is a fragmentary end elevation of the winding element viewed as indicated by the line I3--l3 of Figure 12;

Figure 14 is an enlarged end elevation of the.

of a fragment of one of the strands of wire from which the dust-collecting element to which the invention relates is made; Figure 17 shows the strand in its original form; Figure 18 shows the strand after it has passed through the first wiredeforming element; Figure 19 shows the strand after it has passed through the wire-flattening element; Figure 20 shows the strand after it has passed through the second wire-deforming element; Figure 21 shows the strand after it has passed through the third wire-deforming element. The dash-and-dot lines have been placed on opposite sides of the fragments of the strand in Figures 20 and 21 to emphasize the change produced, in the form of the strands by the third wire-deforming element;

Figure 22 is a view of a length of the dustcotllecting element to which this invention rela es;

Figure 23 is a diagrammatic view which illustrates the formation of the dust-collecting element to which this invention relates;

Figure 24 is what may be described as a skeleton view of a length of the dust-collecting element to which this invention relates;

Figure 25 is an elevation, with parts broken away and in section, of an air cleaner in which the dust-collecting element to which this invention relates is incorporated.

In making a dust-collecting element in accordance with this invention, I take several strands of rather small copper wire and by suitable operations flatten and deform them. The several flattened and deformed strands are then concurrently and together wound around an arbor so that they advance alternately for a distance in one direction and for a different distance in the opposite direction along the axis of the arbor as they advance around it. This procedure is continued indefinitely and as a result thereof there is produced an interstitial tubular element whose components are maintained in the relative positions in which they are wound by a sort of felting action-i. e., by interengagement of the deformations in the contiguous strands. The tubular element after being cut into suitable lengths and impregnated with a suitable liquid,

such as oil, is ready for installation in an air cleaner. If desired, the tubular element may be flattened and stitched longitudinally before it is cut into lengths and impregnated but the flattening and stitching operations are not essential elements of my process. Obviously, the tubular element will offer little resistance to the passage of'air in any direction, will be stable in form and will afford a large area of surfaces which may be coated with liquid. Furthermore, if the pitch or pitches of the turns are properly selected with reference to the width of the group of strands employed, the tubular element will also be, in directions transverse of its axis, of substantially uniform intersticity. And it may be added that because the flat surfaces of the strands are inevitably disposed at all angles in the tubular element, air passing therethrough will be deflected from one surface to another and, therefore, come into contact with a greater area of liquid-coated surface and be more thoroughly cleaned than it would if the flat surfaces were inclined in only one direction.

The machine illustrated in the accompanying drawings automatically performs speedily and economically, among others, the operations, except the flattening and stitching operations, described in the next preceding paragraph.

This machine consists of a suitably supported main frame 58 on one end of which there are mounted two fixtures 5|. Each of these fixtures includes an upstanding arm 52 and from each side of each of the arms 52, there projects a spindle 58 which is adapted to support a spool 58 of rather small copper wire a. To prevent accidental removal of the spool therefrom, there is provided on the outer end of each spindle a removable collar 55.

On the main frame 58, there are also mounted three wire-deforming elements58, 58 and 59, a wire-flattening element 51, a winding element 88 and a shearing element 8I.

The first wire-deforming element 58 includes a pair of upstanding arms 82 which are fixed to the main frame 58. In the arms 82, there are journaled a shaft 88 to which is keyed a fluted roll 88 and, above the shaft 83, a shaft to which there are fixed a pair of normally dependent arms 88. In the free ends of the arms 88, there is joumaled a shaft 81 to which is keyed a fluted roll 88. The flutes in the rolls 88 and 88 extend from one end to the other of the rolls and are formed by cutting gear teeth in the rolls. When one of the arms 88 is in engagement with the set screw 89 which is carried by the adjacent upstanding arm 82, the teeth on the rolls 88 and 88 interfit throughout their lengths but interengage only at one extremity 18 because at all other points they are slightly relieved. So that the arms 88 may be moved angularly about the axis of the shaft 85 to shift the roll 88 to and from the position in which its teeth interfit with the teeth on the roll 84, there is provided on the shaft 85 a handle 1| on which there is adjustably mounted a weight 12 which tends to maintain the arm 88 in engagement with the set screw 89.

The wire-flattening element 51 includes a frame 18 which is fixed to the main frame 58. In the frame 13, through the medium of bushings 18, there is journaled a shaft 15 on whose intermediate portion there is formed a smooth cylindrical roll 18. Above the bushings 14, there are journaled in the frame 13 eccentric bushings 11 and in these eccentric bushings, there is journaled a shaft 18 on whose intermediate portion, there is formed a smooth cylindrical roll 19 and on one of whose ends there is keyed a gear 85 which meshes with a gear 88 which is keyed to the shaft 18. In each of the eccentric bushings 11 there are formed teeth 88 which mesh with a worm 8I which is keyed to a shaft 82 which is journaled in the frame 13 above the bushing. The shafts 82 are connected by sprockets 83 and a chain 88 and their outer ends are squared so that they will fit into a. socketed key. By rotating one of the shafts 82 by means of the key, one may rotate both of the eccentric bushings 11 and thus move the roll 18 toward or away from the roll 19, but it is to be noted that thechain 84 is fitted sufficiently loosely to permit the independent adjustment of the eccentric bushings 11 which may be necessary to render the spacing of the rolls 18 and 19 uniform from end to end.

In the second wire-deforming element 58, the shafts 81 which carry the rolls 89 and 98 are normally connected by gears 9| and 82 which are keyed thereto. The rolls 89 and 98 are annularly grooved and, as Figure 9 clearly shows, the annulets between the annular grooves interiit but because they are slightly relieved do not interengage when the arm 93 is in engagement with the set screw 98. So that the roll 98 may be adjusted longitudinally with respect to the roll 89 and maintained in adjusted position there are provided in the upstanding arms 95 set screws 98 which are adapted to engage the arms 98 by which the roll 98 is carried. To the upstanding arms 95, on the discharge side of the second wiredeforming element, there is secured a part 98 whose function is to prevent the wires emerging from between the rolls 89 and 98 following either of the rolls. The part 98 may be described as a bar through which extend slots 99 equal in num-- bet to the strandsof wire from which the dustcollecting element is to be made and through each of which one of the strands passes after emerging from the rolls 89 and 98. Except as indicated above, the second wire-deforming element 58 does not differ materially from the first wire-deforming element 58.

The third wire-deforming element 59 does not differ materially from the first wire-deforming element 58 except in that the pitch of the teeth in the rolls I88 of the third wire-deforming element is different from the pitch of the teeth in the rolls 84 and 88 of the first wire-deforming element.

To the upstanding arms 82 of thefirst wiredeforming element 58 there are secured shelves I15 and I18 which extend, respectively, toward the fixtures 5| and toward the wire-flattening element 51. Across the outer end of the upper surface of the shelf I15 there extends a rod I11 under which the wires a travel in passing from the spools 58 to the first wire-deforming element 58 and in the upper surface of this shelf there is formed a channel I 8| for the guidance of each wire between the rod I11 and the first wire-deforming element 58. In the shelf I18, which supports the wires a between the first wire-deforming element 58 and the wire-fiat-.

shelf 'I18 supports the wires (1 between the elements between which it extends and in its upper surface there is formed a channel for the guidance of each wire. To the upstanding arms of the third wire-deforming element 59, there are secured flanged shelves I'll and Ill which extend, respectively, toward the third wire-deforming element 09 and toward the winding element 00 and support the wires 1: between the elements between which they extend.

To corresponding ends of the shafts l3 and 39 of the first and second wire-deforming elements there are keyed sprockets I33 and I34 and around these sprockets there passes a chain III. To the opposite end ofthe shaft 03 and to the corresponding end of the shaft 15 of the wire-flattening element I'I there are keyed, respectively, a sprocket I09 and three sprockets I31, I33 and I99. Around the sprockets I03 and I00 passes a chain I90. Around the sprocket I09 .and around a sprocket I9I on the corresponding end of the shaft of the third wire-deforming element 59 on which the lower roll I00 is mounted there extends a chain I92.

The winding element 00 includes a hollow shaft III whose end which is nearest the third wire-deforming element 59 is journaled in an upstanding arm I02 which is secured to the main frame 50. To the opposite end of the shaft "I, there is secured a cup-shaped head I03 which is, through the medium of rollers I I4, journaled in an annular frame I05 which is secured to the main frame 30. To the closed end of the cupshaped head I03, there is secured coaxially with the hollow shaft IOI a stub shaft I03 which proiects into the interior of the head.

On the stub shaft I06 there is mounted through the medium of bearings I0'I a block I00. The block I03 is sufficiently heavy and is mounted on the stub shaft I05 sufficiently off-center that it will not rotate when the stub shaft is rotated. In the outer face of the block I00, there is formed a deep diametrically disposed, vertically extending groove I09. The groove I09 is widened at its inner end, as indicated by the reference character H0, and at its outer end extends into a channel III whose side walls are grooved as indicated by the reference character I I2. In the channel III, there are located plates H3 and H4 and on each of the plates there is formed a tongue H5 which extends into one of the grooves H2. The plates H3 and H4 are adjustably secured to the block I30 by screws I I5 which extend through slots I I1 and on each of them there is formed an ear IIO which extends into the groove I09. In the ear II3 on the plate II3,.there ls journaled a shaft I I9 on whose inner end there is keyed a gear I20 which meshes with a gear I2I which is coaxial with and fixed on the stub shaft I00. On the portion of the shaft II9 which projects beyond the outer face of the block I00, there formed a thread I22. In the ear H9 on the plate II4, there is journaled a shaft I23 to which is keyed a gear I24 which meshes with a gear I25 which is keyed to the shaft H9. The shaft I23 differs from the shaft II9 only in that the pitch of the thread I28 is opposite that .of the thread I22 and in that a head I2I instead of a gear is provided on its inner end.

A tube I20 extends from a point beyond the end of the hollow shaft IOI nearest the third wire-deforming element 59, through the hollow shaft, 9. slot I29 in the wall of the hollow shaft and the head I03to a point beyond the outer end of the block I00. As the drawing clearly shows, the end of the tube I 20 nearest the third wiredeforming element 59 is of funnel-like form and the opposite end of the tube is directed toward the screw-shafts H9 and I23. The tube I 28 is fixed to a block I33 carried by a grooved collar I3I which is slidable on the hollow shaft MI and is slidable in a bearing in the end of the hollow shaft nearest the third wire-deforming element 59 and in a bearing I32 which is secured to the head I03. 0

Parallelly to the hollow shaft I9 I, there extends a shaft I33 which is journaled at its end which is nearest the third wire-deforming element 59 and intermediate its ends in a bracket I34 which is secured to the main frame 50. In the end of the shaft I33 which is furthest from the third wire-deforming element 59, there is formed a cam groove I35 in the form of two equally but oppositely pitched helices joined -at their ends. Into the groove I35 extends the flattened end of a pin I36 which is rotatably mounted in a collar I31 which surrounds a part of the shaft I33 and carries a fork I30 whose prongs straddle the grooved portion of the collar I3I on the hollow shaft IIII. The collar I31 also carries a tube 206 which is secured thereto by a clamp 205. The tube 206 terminates at one end adjacent the funnel-shaped end of the tube I28 and to this end of the tube 200, there is connected one end of a U-shaped tube 200 whose opposite end is directed toward the axis of the tube I28. To the end of the tube 205 distant from that to which the tube 208 is connected, there isconnected one end ofa flexible hose 209 whose opposite end is connected to a source of air or other gaseous fluid under pressure.

'Around sprockets which are keyed respectively to the hollow shaft IN, the shaft I33 and a shaft I39 which extends parallelly to the shafts IN and I33 and is journaled in bearings mounted on the main frame extends a chain I40. 0

The shearing element 6i includes a bracket I which is secured to the main frame 50 and shears 2Il dependently mounted on the bracket by the bolt I42 which pivotally connects its elements. To the upper end of each of the elements of the shears 2| I, there is connected one end of a chain I43 which passes over a pulley I44 and whose opposite end is connected to the bracket I by a spring I45. To the upper end of each of the elements of the shears, there is also pivotally connected a link I 46. The links I40 are pivotally connected to each other and to the lower ends of links I" by a bolt I48. The upper ends of the links I" are connected to the lower end of a rod I49 of magnetic material whose upper end extends into the axis of a solenoid I50 which is fixed to the bracket I4I.

On the side of the main frame 50 adjacent the end of the shaft I33 which is furthest from the third wire-deforming element 59, there is fastened a plate I5I to which is secured a stub shaft I52. On the stub shaft I52 there is mounted a flanged disc I53 which is free to rotate in a clockwise direction when it is viewed as it is shown in Figures 1 and 15. Rotation of the disc in the opposite direction is prevented by the one-way brake I54. Between the disc I53 and the plate I5I, there is mounted on the stub shaft I52 an arm I55 whose upper end is urged by a spring I50 toward the outer end of a rod I51 which is carried by the collar I31 on the shaft I33. Movement of the upper end of the arm I55 toward the outer end of the rod I 51 is limited by the vertical wall of a rabbet I58 in the plate I5I.

To'the upper end of the arm I 55, a lever I59 is connected by a screw I60 which extends through an elongated slot I6I in the lever. On the lower end of the lever I69, there are formed ears I62 which are located on opposite sides of the flange of the disc I53. To the upper end of the lever I59 and to an arm I69 which is secured to the upper end of the arm I55, there is secured a spring I64 which urges the lever downwardly and in a clockwise direction when it is viewed as it is shown in Figures 1 and 15.

On the plate I5I. there is mounted a switch I65 which consists of a bracket I66 secured to the plate I5I and a lever I61 pivotally connected to but electrically insulated from the bracket. The lever I61 carries a pin I68 which is maintained in contact with the flange of the disc I53 by a spring I69. The bracket I66 carries a contact element I10 and the free end of the lever I61 a contact element "I which engages the contact element I10 when the pin I 66 enters the notch I12 in the flange on the disc I53. The contact elements I10 and "I are electrically connected to opposite ends of the solenoid I50 by wires I19 and I14 in one of which is inserted a battery or other source of electricity.

From the main frame 50, there depends a platform I96 on which there is mounted an electric motor I94 and a speed-reduction gear unit I95. On one end of the shaft I96 of the electric motor there is keyed a sprocket I91 and around this sprocket and a sprocket I96 which is keyed to the shaft I39 of the winding element 66 there passes a. chain I99. The other end of the shaft I96 of the electric motor is connected to the input shaft 209 of the speed-reduction gear imit I95 by a coupling "I and to the output shaft 202 of the speed-reduction gear unit there is keyed a sprocket 203 around which and the sprocket I91 on the shaft 15 of the wire flattening element 51 passes a chain 204.

To produce the dust-collecting element b to which the invention relates, a spool 54 of copper wire a, preferably round and 0.007" to 0.0081" in diameter, is placed on each of the spindles 53 of the fixtures 5I. Each strand a of wire is then lead, successively, under the rod I11 on the shelf I15, through one of the channels "I in the shelf I15, between the rolls 64 and 66 of the first wiredeforming element 56, through one of the channels I62 in the shelf I16, between the rolls 16 and 19 of the wire-flattening element 51, through one of the channels in the shelf I16, between the rolls 69 and 90 of the second wire-deforming element 56, through one of the slots 99 in the part 96, over the shelf I19, between the rolls I00 of the third wire-deforming element 59 and over the shelf I60. The several strands a are then grouped and their ends inserted together into the funnel-like end of the tube I26.

After the foregoing procedure has been completed, the handle 1| on the first wire-deforming element 56 and the corresponding handles on the second and third wire-deforming elements 56 and '59 are moved to the positions in which the teeth or annulets on the upper roll of each wire-deforming element interiit with the teeth or annulets on the lower roll thereof and the upper roll of the wire-flattening element 51 is adjusted to the proper position with respect to the lower roll thereof.

Then the electric motor I94 is started and fluid under pressure admitted to the tube 209. Betation of the shaft of the electric motor causes synchronous operation of the wire-deforming, wire-flattening and winding elements at such rates that the portions of the wires a between the adjacent elements are not stretched and do not become undesirably slack. Rotation of the shaft of the electric motor also causes operation of the shearing element, and admission of air under pressure to the tube 209 causes a current of air to flow through the tube I26.

Rotation of the shaft of the electric motor I94 is transmitted to the rolls of the wire-deforming and wire-flattening elements through the speedreduction gear unit I95 and the sprockets and chains which connect it with the shafts of the wire-deforming and wire-flattening elements. The rolls of the wire-deforming and wire-flattening elements grip the wires a, unwind them from the spools 64 and cause them to advance toward the winding element 60. During their passage betweenthe rolls 64 and 66 of the first wiredeforming element 66, the wires are corrugated transversely. During the passage of the wires between the rolls 16 and 19 of the wire-flattening element 51, their sides which are in planes parallel to that of the corrugations produced by the first wire-deforming element 66 are flattened. During their passage between the rolls 69 and 99 of the second wire-deforming element 56, the wires are corrugated longitudinally and in directions at right angles to the directions of the connections produced by the first wire-deforming element 56. During their passage between the rolls of the third wire-deforming element 59, the wires are again corrugated transversely but in directions at right angles to the directions of the corrugations produced by the first wire-deforming ele- T ment 56. Because the pitch of the teeth in the rolls of the third wire-deforming element is different from the pitch of the teeth in the rolls of the first wire-deforming element, the corrugations produced by the third wire-deforming element will not be spaced uniformly with respect to the corrugations produced by the first wiredeforming element. It is preferable, if wire of the preferred size is used as stock, that the rolls of the wire-deforming and wire-flattening elements be so adjusted that when the wires emerge from between the rolls of the third wire-deforming element they will be 0.0018" to 0.0015" thick and 0.022" to 0.032" wide.

It is to be noted that while the transverse corrugations imparted to the wires 41 by the first and third wire-deforming elements are produced principally by bending the wires, the longitudinal corrugations imparted to the wires by the second wire-deforming element are produced principally by stretching the wires. The transverse corrugations impart elasticity to the wires and the longitudinal corrugations which are much narrower and shallower than the transverse corrugations serve principally as liquid-retaining channels in the dust-collecting element into which the wires a are made.

Rotation of the shaft of the electric motor I94 is transmitted to the shaft I39 of the winding element 66 by sprockets I91 and I96 and the chain I99 and from the shaft I39 to the shafts IOI and I33 by the sprockets and chain which connect them. Rotation of the shaft I9I does not cause the screw-shafts I I 9 and I23 to move bodily but does cause them to rotate in opposite direc tions around their respective axes and causes the end of the tube I26 whichis directed toward the screw-shafts H9 and I23 to revolve around them. When the shaft I63 rotates, the collar I31 reciprocates on the shaft I33 and the tube I26 reciprocates in itsbearingsin the hollow shaft III with the result that the end of the tube I28 which is directed toward the screw-shafts H8 and I23 moves constantly back and forth axially of the screw-shafts II! and I23 as it revolves around them.

Initially, the group of strands which is inserted into the tube I28 is advanced therethrough solely by the current of air which flows therethrough. But as the group of strands emerges from the end of the tube I28 which is directed toward the screw-shafts H8 and I23, the end of the group is caught by the screw-shafts and, thereafter, the group is wound on the screwshaits as it emerges from the end of the tube and is advanced through the tube by the joint action of the current of air and the pull exerted on it by reason of the fact that it being wound on the screw-shafts.

The rotary movement of the tube I28 causes each strand of the group which travels therethrough to be wound helically around the others and transforms the group of strands into a loosely twisted, rope-like structure. The combined rotary and reciprocatory movement of the end of the tube I28 which is directed toward the screw-shafts H9 and I23 causes the twisted group of strands, as it emerges from the end of the tube I28, to be wound around the screwshafts for two helical turns in one direction axially of the screw-shafts and for the same number of helical turns in the opposite direction axially of the screw-shafts, alternately, as long as the machine operates. The concurrent rotation of the screw-shafts H9 and I23 about their respective axes constantly moves the tubular element 1) thus formed toward and off the outer ends of the screw-shafts and, consequently, the length of the windings in one direction axially of the screw-shafts will be greater than the length of 40 the windings in the opposite direction and the 45 there will result from operation of the machine illustrated and described a tubular element of indefinite length whose wall is a number of times thicker than the group c of strands of which it is composed and whose constituent strands are maintained in the relative positions in which they are wound by interengagement of the corrugations in the contiguous strands which also serve to prevent the contiguous strands from interfi-tting too closely. The group 0 of strands can be fabricated by the machine illustrated and described into a tubular element whose wall is a number of times thicker than the group of strands because the strands a are elastic and capable of being stretched when the circumference of the body on which they are being wound increases. Because the portions of the strands a adjacent the outer wall of the tubular element b are stretched more than the portions thereof adjacent the inner wall of the tubular element, during fabrication of the tubular element, the tension in the portions of the strands adjacent the outer wall of the tubular element will be greater than the tension in the portions thereof adjacent the inner wall of the tubular element and the tension in the portions of the strands adjacent one end of each winding of the group 0 will be greater than the tension in the portions thereof adjacent the other end of the winding.

From the shafts IIS and I23, the tubular element 1: passes between the elements of the shears 2H and into a trough 2I0 which is supported by the bracket MI.

Each time that the collar I3 moves toward the right on the shaft I33 when the machine is viewed as it is shown in Figures 1 and 15, the rod I51 engages the arm I55 and through the lever I59 causes the disc I53 to rotate through a predetermined angle in a clockwise direction. Once during each revolution of the disc I53, 'the pin I68 on the lever I61 of the switch I65 enters the notch I12 in the flange on the disc I53 and the circuit through the solenoid I50 is closed. When the solenoid is thus energized, the rod I49 is raised, the elements of the shears are brought together and the tubular element severed. When the circuit through the solenoid is opened the solenoid is de-energized and the elements of the shears are moved apart by the springs I45. The frequency of operation of the shears and, consequently, the length of the lengths of tubular element b produced by the machine may of course be varied by adjusting the length of the rod I51.

Because Figure 22 in which there is shown a length of the tubular element 12, does not disclose clearly the construction of the element and it has been found impossible .by depicting the tubular element itself to convey a clear conception of its construction, there have been included in the drawings Figures 23 and 24 which clearly disclose the formation and construction of the tubular element b. InFigures 23 and 24, the part'to which the reference character n is applied represents the core of the group of strands a of copper wire from which the tubular element b is formed. In forming the tubular element b, one end d of the group of strands is connected, temporarily at least, to an arbor, such as the screw-shafts H9 and I23, and the group of strands wound around the arbor for two turns axially of the arbor to the point e; then the direction of winding axially of the arbor is reversed and the group of strands wound around the arbor for two more steeply pitched turns to the point I; from the point 1 the winding proceeds as from the point (1 and the described procedure is repeated indefinitely. In Figures 23 and 24, the portions of the turns of the part 1: which are on the side of the tubular element b which is nearest the observer are shown in heavy solid lines and those which are on the side of the tubular element farthest from the observer are shown in dotted lines. To avoid confusion more than four turns of the part 1:. have not been shown in Figure 23 but in order to illustrate completely the construction of the tubular element b all of the turns of the group of strands which are present in a length of the element b have been represented in Figure 24.

To illustrate how the dust-collecting element to which this invention relates is utilized in an air cleaner, I have shown in Figure 25 of the drawings a combined air cleaner and resonator silencer in which the element is incorporated. The combined air cleaner and resonator silencer shown in Figure 25 includes a shell g in whose upper end there is a generally cylindrical compartment it through whose outer wall extend air intake openings 12 and into whose bottom there extends a tube a which communicates with a tube k which is adapted to be connected to the air intake tube of the carburetor of an internal combustion engine. In the compartment h between the openings i and the tube 1', there is interposed an annular dust-collecting element 1 which consists of a liquid-coated length. of the tubular element b located between screens m and '0, Air which enters the openings 1 must pass through the annular dust-collecting element Z and be freed from dust and other foreign matter before it reaches the carburetor or cylinders of the engine. It will benoted that when a length of the tubular element 17 is bent into annular form, the interstices at the inner edge are made smaller and those at the outer edge larger with the result that a dust-collecting element whose efiiciency is greater at its inner than its outer edge is produced. Although in the combined air cleaner and resonator silencer shown in Figure 25, there is only one turn of the tubular element b in the dust-collecting element, it will be understood that several turns of the tubular element, superposed radially and/or axially, may be employed in a dust-collecting element if suiflcient space is available and a greater volume of dust-collecting element is desired.

I claim: 7

r 1. The method of making a dust-collecting element which consists of winding a strand :around an axis so that it advances alternately in one direction and in the opposite direction along the axis as it advances around it, the distance of advance in one direction along the axis being greater than in the other so that a body of increasing length is produced.

2. The method of making a dust-collecting element which consists of winding a group of fiattened and deformed strands around an axis so that it advances alternately in one-direction and in the opposite direction along the axis as it advances around it, the distance of advance in one direction along the axis being greater than in the other so that a body of increasing length is produced.

3. The method of making a dust-collecting ele ment which consists of winding a twisted group of strands around an axis so that it advances alternately in one direction and in the opposite direction along the axis as it advances around it, the distance of advance in one direction along the axis being greater than in the other so that a body of increasing length is produced.

4. The method of making a dust-collecting element which consists of winding a strand around an axis so that it advances alternately in opposite directions along the axis as it advances around it and simultaneously advancing the body thus produced along the axis.

5. An interstitial body in which there is included a strand of dense, deformation resisting material wound upon itself lengthwise and around the axis of the body a plurality of times with windings of diiferent length in one direction than the other lengthwise of the body.

6. An interstitial body which includes an element wound upon itself lengthwise and around the axis of the body a plurality of times with windings of different pitch and length in one direction than the other lengthwise of the body.

7. An interstitial body which includes a group of deformed strands wound upon itself lengthwise and around the axis of the body a plurality of times with windings of diiierent length in one direction than the other lengthwise of the body.

8. An interstitial body which includes an element woundrupon itselflengthwise and around the axis of the body a plurality of times with windings of different length in one direction than includes a group of deformed strands wound upon the other lengthwise of the body bent into generally ring-like form.

9. The method of making a body which consists of winding a strand around an axis so that it advances alternately in opposite directions 5 along the axis as it advances around it and simultaneously advancing the body thus produced along the axis.

10. An interstitial dust collecting body which includes an element wound upon itself length- 1 wise and around the axis of the body a plurality of times with windings of greater length in one direction than the other lengthwise of the body. 1

11. An interstitial dust collecting body which 15 itself lengthwise and around the axis of the body a, plurality of times with windings of greater length in one direction than the other lengthwise of the body.

12. An interstitial dust collecting element which includes a loosely twisted group of flat metal strands which have in them angular-1y related transversely extending corrugations and smaller lengthwise extending corrugations wound upon itself lengthwise and around the axis of the element a plurality of times with windings in one direction lengthwise of the element of lesser length than and only partly overlapping preceding windings in the other direction lengthwise of the element and windings in the other direction lengthwise of the element of greater length than and completely overlapping and in one direction lengthwise of the element extending beyond preceding windings in the first mentioned direction lengthwise of the element. 35

13. An interstitial dust collecting element which includes a loosely twisted group of strands wound upon itself lengthwise and around the axis of the element a plurality of times with windings in one direction lengthwise of the body of lesser length than and only partly overlapping preceding windings in the other direction lengthwise of the body and windings in the other direction lengthwise of the body of greater length than and completely overlapping and in one direction 45 lengthwise of the body extending beyond preceding windings in the first mentioned direction lengthwise of the body.

14. The method of making a dust collecting element which consists of loosely twisting a group of deformed strands, winding the loosely twisted group of deformed strands around an axis so that it advances alternately in opposite directions along the aims as it advances around it and simultaneously advancing the body thus produced 55 along the axis, and severing the body thus produced into lengths.

15. The method of making a body which consists of winding a strand around an axis so that it advances in opposite directions along the axis as it advances around it and simultaneously advancing the body thus produced along the axis, and severing the body thus produced into lengths.

16. The method of making a dust collecting element which consists of winding 21. group of metal strands around an axis so that it advances alternately in one direction and in the opposite direction along the axis as it advances around it, the distance of advance in one direction along the axis being greater than in the other so that a 70 body of increasing length is produced HARTWELL W. WEBB. 

